Display device with plasma display panel

ABSTRACT

In a display device, attached to a plate-type chassis ( 2 ) is a PDP ( 1 ) having a display screen on which videos are displayed and a circuit board ( 9 ) on which a circuit driving the PDP ( 1 ) is arranged. The circuit board ( 9 ) is shielded with respect to the PDP ( 1 ) thanks to the chassis ( 2 ), and thus does not receive any unwanted radiation noise radiated by the PDP ( 1 ). The display device further includes a back cover ( 6 ) and a cabinet ( 7 ) each having conductivity. The back cover ( 6 ) and the cabinet ( 7 ) house therein the PDP ( 1 ) and the circuit board ( 9 ) attached to the chassis ( 2 ). The back cover ( 6 ) and the cabinet ( 7 ) are both electrically insulated from the chassis ( 2 ). Therefore, any unwanted radiation noise from the PDP ( 1 ) and the circuit on the circuit board ( 9 ) is stopped leaking to the outside.

TECHNICAL FIELD

The present invention relates to display devices equipped with plasmadisplay panels and, more specifically, to a display device preventingany unwanted radiation noise from leaking to the outside.

BACKGROUND ART

Generally, such display device comes together with a circuit board onwhich a circuit driving the plasma display panel (hereinafter, referredto simply as PDP (Plasma Display Panel)) is arranged. The problem hereis, such circuit driving the PDP easily generates electromagnetic wavesas does subject electric signals to digital processing therein. Theelectromagnetic waves are also generated by PDP itself. That is, the PDPand its driving circuit are the source of unwanted radiation noise(hereinafter, referred to as EMI (Electro-Magnetic Interference). Thisis the reason why research and development for a display device havingshielding effects has been active to prevent the EMI-from leaking to theoutside.

Such display device is the one, for example, disclosed in JapanesePatent Laid-Open Publication No. 9-172267. FIG. 25(a) is a slanted viewshowing the structure of the main body of the display device disclosedin the publication. FIG. 25(b) is a view of a section taken along with aone-dot chain line A-A′ shown in (a) of the same drawing, and viewedfrom the direction of an arrow B. In FIGS. 25(a) and (b), frames 251 areeach made of a conductor typified by aluminum, and house a PDP and itsdriving circuit in a space enclosed thereby. Among those frames 251, apart placed at the rear of the display device is provided with a backcover 252, which is made of plastic. Also among those frames 251, a partplaced at the front of the display device is provided with a front cover253, which is also made of plastic. Therefore, approximately the entireparts inside of the front cover 253 are covered by the conductors(frames 253), and the main body can show the shielding effects.

However, the shielding effects thus provided to the above main body onlysuppresses the EMI leaking to the outside of the main body, and the EMIradiated from the PDP just loops to the driving circuit side. As aresult, signal processing carried out by the driving circuit becomesproblematically unstable.

Therefore, an object of the present invention is to provide a displaydevice which can make a driving circuit stably operate with moresatisfactory shielding effects.

DISCLOSURE OF THE INVENTION

The above object is attained by the following aspects. Here, thoseaspects include such specific limited matters as below, and therewith,specific technical effects are achieved.

A first aspect is directed to a display device for displaying a video ona screen thereof, comprising:

a plasma display panel (hereinafter, referred to as PDP(Plasma DisplayPanel)) structuring the screen;

a circuit board on which a circuit for driving the PDP is arranged;

a chassis formed like a plate made of conductive materials, to one planethereof, the PDP is attached, and on the other plane thereof, thecircuit board is mounted; and

an exterior unit being conductive, and housing the PDP and the circuitboard having attached to the chassis, wherein

the chassis shields the circuit board so as to prevent any unwantedradiation noise emitted by the PDP from looping into the circuit on thecircuit board,

the exterior unit prevents, with shielding effects, the unwantedradiation noise emitted by the internally-housed PDP and the circuit onthe circuit board from leaking to the outside, and the chassis and theexterior unit are electrically insulated from each other.

In the display device according to the first aspect, the chassis shieldsthe circuit, and the exterior unit shows shielding effects. With suchdouble shield structure, the present display device first prevents anyunwanted radiation noise emitted by the PDP from looping into thecircuit on the circuit board, and thus the driving circuit of the PDPcan stably operate. Further, with the double shield structure, unwantedradiation noise from the PDP and the circuit is stopped leaking to theoutside of the exterior unit.

A second aspect is directed to a display device for displaying a videoon a screen thereof, comprising:

a plasma display panel (hereinafter, referred to as PDP(Plasma DisplayPanel)) structuring the screen;

a circuit board having a circuit for driving the PDP is arranged on asubstrate;

a chassis formed like a plate made of conductive materials, to one planethereof, the PDP is attached, and on the other plane thereof, thecircuit board is mounted;

a cabinet being conductive, and covering a front side of the chassis;

a back cover being conductive, and covering a back side of the chassis;and

a bracket being insulative, and fixed to the chassis so as to supportthe cabinet and the back cover, wherein

the cabinet and the back cover

are, when covering the chassis to which the PDP and the circuit boardare fixed, supported by the bracket, electrically continued, andelectrically insulated from the chassis, and thereby show shieldingeffects, and

the chassis is electrically insulated from the circuit, and thereby,shields the circuit board and prevents unwanted radiation noise emittedby the PDP from looping into the circuit.

In the display device according to the second aspect, the cabinet andthe back cover house therein the chassis to which the PDP and thecircuit on the circuit board are fixed, and electrical continuity isthus established. Therefore, the cabinet and the back cover both showshielding effects. Also, the chassis shields the circuit. With suchdouble shield structure, the present display device first prevents anyunwanted radiation noise emitted by the PDP from looping into thecircuit on the circuit board, and thus the driving circuit of the PDPcan stably operate. Further, with the double shield structure, theunwanted radiation noise from the PDP and the circuit is stopped leakingto the outside of the cabinet and the back cover.

According to a third aspect, in the second aspect, the display devicefurther comprises an adhesive sheet used to attach the PDP to thechassis, and

the adhesive sheet is insulative.

According to the third aspect, the PDP can be easily attached to thechassis, and further, the PDP and the chassis can be electricallyinsulated from each other.

According to a fourth aspect, in the second aspect, in the chassis, afirst boss is integrally formed,

the substrate is insulative, and in a predetermined position of thesubstrate, a through hole is formed, and

the circuit board is fixed to the first boss by a screw after insertedinto the through hole, and thereby, the circuit arranged on thesubstrate and the chassis are electrically insulated from each other.

According to the fourth aspect, the first boss is integrally formed inthe chassis, and thus there is no more need to structure a component inadvance to attach the circuit board to the chassis. Accordingly, thenumber of components of the display device is reduced, and themanufacturing process of the display device can be simplified.

According to a fifth aspect, in the second aspect, the bracket is eachattached to four corners of the chassis, and

the front cover and the back cover are both supported by the fourbrackets attached to each of the corners.

According to the fifth aspect, even if the cabinet and back cover areprovided with some impactive forces, thus provided impactive forces arenot directly given to the chassis, and absorbed by four bracketssupporting the cabinet and the back cover. Therefore, the maincomponents of the display device such as the PDP and the circuit boardcan be protected from the impactive forces coming from the outside.

According to a sixth aspect, in the second aspect, the display devicefurther comprises a base being conductive, and determining a position ofthe screen with respect to a placement plane by having the chassisattached thereto, wherein

the base is electrically insulated from the chassis, and electricalcontinuity is established with the back cover.

According to the sixth aspect, the base is electrically insulated fromthe chassis, and electrical continuity is established with the backcover. Therefore, the reception sensitivity for the radio (video signal)is improved in the display device.

According to a seventh aspect, in the second aspect, the display devicefurther comprises:

a top positioning unit having integrally attached to the chassis, andhaving a cylindrical hole whose center axis is parallel to a verticaldirection opened from a flat lower end plane thereof;

an insulation layer formed inside, entirely, and on a lower end plane ofthe hole;

a base being conductive, and supporting the chassis so as to determine aposition of the screen with respect to a placement plane thereof; and

a bottom positioning unit shaped like a rod, wherein

the base includes a lug in which a through hole is formed, a center axisof the through hole is parallel to the vertical direction, and an upperend plane thereof is formed flat,

the bottom positioning unit is fixed to the base by going through thethrough hole of the base and the hole formed in the top positioningunit, and thereby, the upper end plane of the lug determines a positionof the lower end plane of the top positioning unit, and

the insulation layer makes the top positioning unit and the baseinsulated from each other.

With such structure according to the seventh aspect, the base iselectrically insulated from the chassis, and electrical continuity isestablished between the base and the back cover.

According to an eighth aspect, in the second aspect, the display devicefurther comprises a spacer made of conductive materials in which a firstthrough hole is formed, wherein

in the chassis, a second boss is integrally formed,

at a predetermined position of the back cover, a second through hole isformed, and

a screw inserted into the first through hole and the second through holeis fixed to the second boss, and thereby, the back cover is attached tothe chassis while kept electrically insulated therefrom.

According to the eighth aspect, the second boss is integrally formed inthe chassis, and thus there is no more need to structure a component inadvance to attach the circuit board to the chassis. Accordingly, thenumber of components of the display device is reduced, and themanufacturing process of the display device can be simplified.

Further, with the structure of the eighth aspect, the back cover isattached to the chassis while kept electrically insulated therefrom.

According to a ninth aspect, in the fifth aspect, among the four, thebracket attached on the chassis abuts to the inside of the back cover,and supports the back cover.

According to the ninth aspect, the bracket supports the back coverattached to the chassis. Therefore, displacement of the back coverhardly occurs.

According to a tenth aspect, in the firth aspect, the two brackets fixedon the chassis are each provided with a rib, and the rest are eachprovided with a screw hole,

the cabinet is provided with a hook on the upper part thereof, and athrough hole on the lower part thereof,

the hook is engaged with and stopped by the ribs, and by the screwinserted into the through hole being fixed to the screw hole, therebythe cabinet is supported by the four brackets.

With the structure of the tenth aspect, the cabinet is attached to thechassis while kept electrically insulated therefrom.

According to an eleventh aspect, in the second aspect, the cabinet andthe back cover touch to each other when supported by the brackets.

According to the eleventh aspect, electrical continuity is establishedbetween the front cover and the back cover by simply making those touchto each other.

According to a twelfth aspect, in the second aspect, the display devicefurther comprises a base for making the chassis having the PDP and thecircuit board attached thereto self-standing, wherein

the cabinet and the back cover are each detachable to the brackets.

According to the twelfth aspect, the cabinet and the back cover are eachdetachable to the brackets. Therefore, in order to access the inside ofthe display device, there only needs to remove either the front cover orthe back cover. That is, according to the twelfth aspect, theaccessibility to the inside of the display device can be improved.

According to a thirteenth aspect, in the second aspect, the displaydevice further comprises an elastic solid being conductive, wherein

the cabinet and the back cover sandwich the elastic solid when supportedby the brackets.

According to the thirteenth aspect, the elastic solid lies between thecabinet and the back cover and thus is closely attached to both ofthose. Further, the elastic solid is conductive, and thus helps to wellestablish electrical continuity between the cabinet and the back cover.Therefore, the shielding effects achieved by the cabinet and the backcover can be improved to a greater degree.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded slanted view showing the entire structure of adisplay device according to a first embodiment of the present invention;

FIG. 2 is a diagram for demonstrating a manner of attaching a PDP 1 to achassis 2 shown in FIG. 1;

FIG. 3 is an enlarged view of an upper left corner of the chassis 2shown in FIG. 1;

FIG. 4 is a slanted view showing the back of the chassis 2 shown in FIG.1;

FIG. 5 is a diagram for demonstrating a manner of attaching circuitboards 9;

FIG. 6 is a diagram showing the chassis 2 having attached with any oneof the circuit boards 9;

FIG. 7 is an exploded slanted view showing the structure of apositioning unit 10;

FIG. 8 shows a vertical section of the exploded positioning unit 10shown in FIG. 7;

FIG. 9 shows enlarged views of a vertical section and a horizontalsection of the positioning unit 10 after assembled;

FIG. 10 is a front view of a bracket 3 b of FIG. 1;

FIG. 11 is a top view of the bracket 3 b of FIG. 1;

FIG. 12 is a side view of the bracket 3 b of FIG. 1;

FIG. 13 is a front view of a bracket 3 c of FIG. 1;

FIG. 14 is a top view of the bracket 3 c of FIG. 1;

FIG. 15 is a side view of the bracket 3 c of FIG. 1;

FIG. 16 is a view of the chassis 2, viewed from the side, having thebrackets 3 a to 3 d attached;

FIG. 17 is a front view of a back cover 6 of FIG. 1;

FIG. 18 is a diagram for demonstrating a manner of attaching the backcover 6 to the chassis 2;

FIG. 19 is a diagram for demonstrating the electrical relationshipbetween the back cover 6 and the chassis 2;

FIG. 20 is a section view of a section, taken along with a line C-C′ ofFIG. 1, viewed from the direction of an arrow D;

FIG. 21 is a diagram for demonstrating a manner of attaching the cabinet7 to the chassis 2;

FIG. 22 is an exploded slanted view showing the entire structure of adisplay device according to a second embodiment of the presentinvention;

FIG. 23 is an enlarged view for demonstrating a section of a gasket ofFIG. 22;

FIG. 24 is a section view for demonstrating the inside of the cabinet 7of FIG. 22; and

FIG. 25 is a diagram demonstrating the structure of the main bodyapplied to a conventional display device.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a slanted view showing the entire structure of a displaydevice, having a PDP equipped thereto, according to a first embodimentof the present invention. The display device is a device displayingvideos on a screen thereof. FIG. 1 shows, as general components for thedisplay device, a PDP (Plasma Display Panel) 1, a chassis 2, fourbrackets 3 a to 3 d, a base 4, two bottom positioning units 5 a and 5 b,a back cover 6, and a cabinet 7. Herein, FIG. 1 shows other components,and those are appropriately described whenever necessary.

The PDP 1 is a part enclosed by slashes. The PDP 1 is the one structuredby grids of electrodes encased within two flat glass panels separatedfrom each other by ionizing gas. In such structure, by applying energyto any selected electrode, the gas is ionized, and light is emitted at apredetermined position. By utilizing such phenomenon, the PDP 1structures a screen for displaying videos thereon. Here, forconvenience, presumably, a longer side of the PDP 1 is a in length, anda shorter side thereof is b in length.

The chassis 2 is made of die-cast conductive materials. As for theconductive materials, aluminum is preferably selected. If so, thedisplay device can be accordingly reduced in weight. As shown in FIG. 2,and the like, the chassis 2 is board-like, and the outer shape thereofis approximately rectangular. One plane 21 of the chassis 2 is formedflat. The plane 21 is formed in accordance with the shape of the PDP 1.In this embodiment, the plane 21 is selected as to be rectangular inshape. Thus, for convenience, a longer side of the plane 21 is alsopresumed to be a in length, and a shorter side thereof b in length. Tothe plane 21, the PDP 1 is attached. In this embodiment, as shown inFIG. 2, the PDP 1 is attached to the plane 21 via a double-facedadhesive sheet 8. Here, the adhesive sheet 8 is made of insulation, andadhesive on both sides. This adhesive sheet 8 works as an insulationlayer formed between the PDP 1 and the chassis 2, and thus the PDP 1 isattached to the chassis 2 but is electrically insulated therefrom. Onthe chassis 2, a periphery 22 is formed integrally around the plane 21.

Refer back to FIG. 1. To each corner of the chassis 2, a bracket fixingpart having screw holes formed therein is integrally attached. The screwholes provided in each of the bracket fixing parts are used to fix thebrackets 3 a to 3 d, respectively, to the chassis 2. Here, FIG. 3 is anenlarged view of the area around the upper-left corner of the chassis 2when viewed from the direction of an arrow A of FIG. 1 (that is, aviewer's point of sight). As for the corner shown in FIG. 3, bracketfixing parts 23 b to 25 b, which are small and tongue-shaped, areprotruding from the periphery 22. The bracket fixing parts 23 b to 25 beach have a screw hole formed therein to fix the bracket 3 b thereto byscrews. Similarly, bracket fixing parts 23 a to 25 a for the bracket 3 aare integrally attached to the upper-right corner of the chassis 2 (seeFIG. 1). To the lower-left corner of the chassis 2, bracket fixing parts23 c and 24 c for the bracket 3 c are integrally attached, and to thelower-right corner thereof, integrally attached are bracket fixing parts23 d and 24 d for the bracket 3 d (see FIG. 1). Here, the bracket fixingparts 23 a to 25 a, the bracket fixing parts 23 c and 24 c, and thebracket fixing parts 23 d and 24 d are all the same as the bracketfixing parts 23 b to 25 b, differed only in position to be formed at,and thus are neither described nor shown in detail.

FIG. 4 is a slanted view of the chassis 2 viewed from the direction ofan arrow B of FIG. 1. In other words, FIG. 4 is a view of a planeopposite to the plane 21 (back of the chassis 2). In FIG. 4, arranged onthe back of the chassis 2 are a first boss 26, second bosses 27 a to 27d, top positioning units 28 a and 28 b, and frames 29.

Note herein that the first boss 26, the second bosses 27 a to 27 d, thetop positioning units 28 a and 28 b, and the frames 29 are allintegrally attached to the chassis 2. With such integral structure, thenumber of components required to assemble the display device can bereduced. Accordingly, the manufacturing process of the display devicecan be simplified, and what is better, the manufacturing cost can bereduced.

Here, FIG. 4 shows only one first boss 26, but the actual number thereofis plural as many as through holes 93 formed in circuit boards 9 (seeFIG. 5). In each of the first bosses 26, a screw hole is formed. In thesecond bosses 27 a to 27 d, a screw hole is each formed to fix the backcover 6 by screws. The top positioning units 28 a and 28 b are placed onthe lower left and right of the chassis 2, and are a part of apositioning unit 10, which will be later described. The frames 29 areformed for the purpose of reinforcing the chassis 2. Further, the frames29 are arranged in a ladder shape, and segment a space on the back ofthe chassis 2. Thus, several spaces α are formed on the back of thechassis 2. The above-described first bosses 26 are each placed withinthe spaces α.

With reference to FIG. 5, described next is a manner of attaching thecircuit boards 9 to the chassis 2 of FIG. 2. In FIG. 5, the circuitboard 9 is the one, typically as a PCB (Printed Circuit Board), havingvarious circuit elements and leads for their connections (hereinafter,such circuit elements and leads are collectively referred to as “circuit92”) arranged on a substrate 91 made of insulation. The circuit 92 istypified by a digital signal processing circuit for displaying videos onthe PDP 1. Also, each substrate 91 is provided, wherever necessary, withthe through holes 93. A screw 94 is first inserted into thecorresponding through hole 93, and then fixed to the first boss 26. Inthis manner, each circuit board 9 is attached to the chassis 2 to beplaced in each corresponding space α.

FIG. 6 shows the chassis 2 having a certain circuit board 9 attachedthereto. Here, for convenience, FIG. 6 only shows the area around thecertain circuit board 9 for description. In FIG. 6, a shaded part βshows the area around the screws 94 each fixed to the first bosses 26(not shown in FIG. 6). The shaded part β has no circuit element and-leadstructuring the circuit 92 arranged thereon. Therefore, the circuit 92is mounted to the chassis 2 through the substrate 91 made of insulation,and the circuit 92 and the chassis 2 can be electrically insulated fromeach other.

Note here also that, as described above, the circuit boards 9 are allarranged to be in the spaces α, and thus the circuit boards 9 are allplaced not to stick out from the chassis 2. To be more specific, whenthe chassis 2 is viewed from the direction of the arrow A of FIG. 1, thecircuit boards 9 fit behind the chassis 2 and are completely invisible.The chassis 2 accordingly shields the circuit 92 from the EMI emittedfrom the PDP 1.

Here, other circuit boards 9 not shown in FIG. 6 are also attached tothe chassis 2 similarly to the above. That is, the chassis 2 alsoshields every other circuit 92 on those circuit boards 9 from the EMIradiated from the PDP 1.

With reference to FIGS. 1 to 6, described above is the arrangement ofthe PDP 1, the chassis 2, and the circuit boards 9. As already describedin the foregoing, the circuits 92 are each electrically insulated fromthe PDP 1 (see FIGS. 2 and 6). Also, the chassis 2'shields thosecircuits 92 (see FIG. 6). With such structure, the EMI radiated from thePDP 1 will find difficult to loop towards the circuit boards 9. As aresult, the circuits 92 can correctly operate almost without beingaffected by the EMI.

FIG. 7 is an exploded slanted view showing the entire structure of thepositioning unit 10. FIG. 8 shows a vertical section of the positioningunit 10 taken along with a line E-E′ shown in FIG. 7 and viewed from thedirection of an arrow F. FIG. 9(a) shows a vertical section of thepositioning unit 10 of FIGS. 7 and 8 after assembled. FIG. 9(b) shows anenlarged view of a horizontal section of the positioning unit 10 takenalong with a line G-G′ shown in (a) of the same drawing viewed from thedirection of an arrow H. Here, for convenience of description below,FIGS. 7 to 9 all show an x-axis, y-axis, and z-axis being orthogonal toone another. Here, the y-axis is an axis parallel to the verticaldirection. The z-x plane is a plane parallel to the horizontal plane.

With reference to such FIGS. 7 to 9, described now is about thepositioning unit 10. The positioning unit 10 determines the position ofthe PDP 1 so that the PDP 1 is perpendicular to the placement plane ofthe completely-assembled display unit (hereinafter, simply referred toas “complete unit”). Here, the positioning unit 10 includes, as shown inFIGS. 7 and 8, the top positioning units 28 a and 28 b, sacs 110 a and101 b, at least two conductive strips 102 a and 102 b, conductive blocks103 a and 103 b, a base 4, and the bottom positioning units 5 a and 5 b.

The top positioning unit 28 a is structured by a barrel-shaped block, alower plane of which is parallel to the z-x plane. The block has a hole281 a formed therein. As shown in FIG. 8, the hole 281 a is so formed asto be approximately cylindrical, and a center axis thereof is parallelto the y-axis. Further, the hole 281 a is open at the lower end of thebarrel-shaped block, while the upper end of the hole 281 a is closed.Here, the top positioning unit 28 b is substantially formed the same asthe top positioning unit 28 a, and thus is neither shown nor describedin detail. Such top positioning units 28 a and 28 b are so placed that,from a center point of the side of the chassis 2 parallel to the x-axis,a distance to the center axis of the hole 281 a is equal to a distanceto the center axis of the hole 281 b.

The sacs 101 a and 101 b are each made of sheet insulation with apredetermined thickness shaped like a bag. To be more specific, theouter shapes of the sacs 101 a and 101 b are cylindrical so as to beengageable with the holes 281 a and 281 b. The upper parts of the sacs101 a and 101 b are closed, but the lower parts thereof are open.Further, the sacs 101 a and 101 b are each formed wider towards theaperture at the bottom, whereby the lower plane is formed to be parallelto the z-x plane. The lower planes of the sacs 101 a and 101 b are soformed as to fit to the shapes of the lower planes of the toppositioning units 28 a and 28 b.

The conductive strips 102 a and 102 b are made of conductive materials,and the longer sides thereof are each so determined in length as tocover the depth of the holes 281 a and 281 b. On the other hand, theshorter sides of the conductive strips 102 a and 102 b are so determinedas to be fit inside of the holes of the sacs 101 a and 101 b.

The conductive blocks 103 a and 103 b are made of conductive materialsformed almost in rectangular parallelepiped. The conductive blocks 103 aand 103 b each have a through hole formed therein, and a diameterthereof is substantially the same as that of the holes 281 a and 281 b,respectively.

The base 4 is made of conductive materials formed in plate, and supportsthe chassis 2 in such state that the PDP 1 is positioned with respect tothe placement plane. Here, as is supporting a complete unit, the base 4is preferably made of high-density metal. The lower plane of the base 4is formed to be parallel to the z-x plane, and if the complete unit isimmovably placed, that is the part where abutting to the position forplacement (e.g., floor). Also, the lower plane has recesses 41 a and 41b (see FIG. 8) formed therein with a predetermined interval, and therecesses 41 a and 41 b each have a screw hole formed therein.

Lugs 42 a and 42 b are formed on the upper plane of the base 4 to bedirectly above the recesses 41 a and 41 b. The upper planes of the lugs42 a and 42 b are formed to be parallel to the z-x plane.

Further, formed in the base 4 is a cylindrical through hole 43 a, whichgoes through the recess 41 a and the lug 42 a. Similarly, anothercylindrical through hole 43 b going through the recess 41 b and the lug42 b is formed. Note herein that, as for the base 4, center axes of thethrough holes 43 a and 43 b are both so determined as to locatesubstantially equal from the center of the side parallel to the x-axis,and designed as to be substantially parallel to the y-axis. Also, adistance between those center axes of the through holes 43 a and 43 b issubstantially equal to a distance between the center axes of the holes281 a and 281 b. Further, the through holes 43 a and 43 b aresubstantially equal in internal diameter to the sacs 101 a and 101 b.

The bottom positioning unit 5 a is made of conductive materials, and asshown in FIG. 8, includes a rod 51 a and a head 52 a. The outer diameterof the rod 51 a is substantially the same as the internal diameter ofthe sac 101 a. The longitudinal length of the rod 51 a is so determinedas to reach the bottom of the sac 101 a when the positioning unit 10 isassembled. The head 52 a is a plate-type member having through holesformed in the vicinity of both ends thereof. To one end of the rod 51 a,the center part of the head 52 a is attached. The bottom positioningunit 5 b is substantially the same as the bottom positioning unit 5 a,and thus is not described again.

With reference to FIGS. 7 to 9, described next is a manner of assemblingsuch structured positioning unit 10. First, the rod 51 a and a rod 51 bgo through the through holes 43 a and 43 b, respectively. Then, screws104 a and 104 b go through the through holes of the head 51 a and a head51 b, respectively, and are fixed to screw holes formed in the recesses41 a and 41 b. In this manner, the bottom positioning units 5 a and 5 bare both fixed to the base 4. At this time, the rods 51 a and 51 bpartially protrude from the lugs 42 a and 42 b. The parts protrudingfrom the lugs 42 a and 42 b go through the through holes of theconductive blocks 103 a and 103 b.

Here, to the inner wall of the sac 101 a, the conductive strip 102 a isfixed. At this time, preferably, one end of the conductive strip 102 ais so fixed as to abut to the bottom of the hole. The conductive strip102 a is then fixed along the inner wall starting from the bottom of thehole towards the aperture. The conductive strip 102 a is then bentoutward at the aperture, and the other end thereof is fixed on the lowerplane of the sac 101 a. Similarly to the conductive strip 102 a, theconductive strip 102 b is fixed to the sac 101 b. The sacs 101 a and 101b are, after the conductive strips 102 a and 102 b are respectivelyfixed therein, each pushed into the hole 281 a of the top positioningunit 28 a and the hole 281 b of the top positioning unit 28 b.

The rods 51 a and 51 b protruding from the conductive blocks 103 a and103 b are inserted into the holes 281 a and 281 b, wherein the sacs 101a and 101 b are now engaged. Thereafter, although not shown in detail,the top positioning unit 28 a and the bottom positioning unit 5 a arefixed to each other by screws, and the top positioning unit 28 b and thebottom positioning unit 5 b are also fixed to each other by screws. As aresult, the chassis 2 is correctly positioned on the upper planes of thelugs 42 a and 42 b through the conductive blocks 103 a and 103 b.Accordingly, the screen of the PDP 1 is positioned perpendicular to theplacement plane (that is, the lower plane of the base 4).

Note herein that, as shown in FIGS. 9(a) and (b), the sac 101 a works asan insulation layer (see back-slashed parts) on the lower plane of thetop positioning unit 28 a and the inner wall of the hole 281 a thereof.Onto the inner wall of the hole formed in the sac 101 a, the conductivestrip 102 a is attached. Similarly, the sac 101 b works as an insulationlayer on the lower plane of the top positioning unit 28 b and the innerwall of the hole 281 b thereof. Onto the inner wall of the hole formedin the sac 101 b, the conductive strip 102 b is attached. With suchstructure, once the positioning unit 10 is assembled, electricalcontinuity is established between the base 4 and the conductive block103 a through the bottom positioning unit 5 a and the conductive strip102 a. Electrical continuity is also established therebetween if thebase 4 directly abuts to the conductive block 103 a. Similarly,electrical continuity is established between the base 4 and theconductive block 103 b. However, by the sacs 101 a and 101 b working asinsulation layers, the base 4 and the chassis 2 made of aluminum areelectrically insulated from each other.

FIG. 10 is a front view of the bracket 3 b. To make clear the relationwith FIG. 1, shown in FIG. 10 is only the bracket 3 b viewed from thedirection of the arrow B of FIG. 1. FIG. 11 is a top view of the bracket3 b, and the bracket 3 b is viewed from the direction of an arrow I ofFIG. 10. FIG. 12 is a side view of the bracket 3 b, and the bracket 3 bis viewed from the direction of an arrow J of FIG. 10. For convenienceof description below, FIGS. 10 to 12 all show an x-axis, y-axis, andz-axis being orthogonal to one another. Here, the y-axis is an axisparallel to the vertical direction. The z-x plane is a plane parallel tothe horizontal plane. Described below is about the bracket 3 b withreference to FIGS. 10 to 12.

In FIGS. 10 to 12, the bracket 3 b is injection molded and made ofinsulation. The bracket 3 b includes, generally, a frame 31 b, chassisfixing members 32 b to 34 b, a joint member 35 b, a top plate 36 b, anda rib 37 b. The frame 31 b is a part enclosed by dots in FIGS. 10 to 12.The frame 31 b is structured by two plates 311 b and 312 b which are soconnected as to form an angle, substantially, of 90 degrees. In FIG. 10,the upper and lower surfaces of the plate 311 b are indicated parallelto the z-x plane, and the center axis thereof is indicated parallel tothe x-axis. Also, therein, the right and left surfaces of the plate 312b are indicated parallel to the y-z plane, and the center axis thereofis indicated parallel to the y-axis.

The chassis fixing members 32 b to 34 b are members to fix the bracket 3b to the back of the corner located at the upper left of the chassis 2.Described below is an exemplary specific structure of the chassis fixingmembers 32 b to 34 b. The chassis fixing member 32 b is in the shape oftongue, and protrudes from one end of the plate 311 b (which is left endin FIG. 10) to be parallel to the x-y plane. Formed in the chassisfixing member 32 b is a through hole 321 b, a center axis of which isparallel to the z-axis (see FIG. 12). The chassis fixing member 33 b isalso in the shape of tongue, and protrudes from one end of the plate 312b (which is lower end in FIG. 10) to be parallel to the x-y plane.Formed in the chassis fixing member 33 b is a through hole 331 b, acenter axis of which is parallel to the z-axis (see FIG. 12). Also, thechassis fixing member 34 b is in the shape of tongue, and protrudes fromthe other ends of the plates 311 b and 312 b (which are right end of theplate 311 b, and upper end of the plate 312 b in FIG. 10) to be parallelto the x-y plane. Formed in the chassis fixing member 34 b is a throughhole 341 b, a center axis of which is parallel to the z-axis (see FIG.11). Here, all undersides of the chassis fixing members 32 b to 34 b areincluded in a single plane parallel to the x-y plane.

The joint member 35 b is a back-slashed part in FIGS. 10 and 11. Thejoint member 35 b is a plate-type member almost in rectangular, and usedto join the frame 311 b and the top plate 36 b to each other. As shownin FIG. 10, the joint member 35 b is so arranged in between the chassisfixing members 32 b and 33 b. One end of the joint member 35 b isintegrally connected to the lower end of the plate 311 b of FIGS. 10 to12, and the other end thereof is integrally connected to one side of thetop plate 36 b. Note here that the surface of the joint member 35 b is apart of the plane orthogonal to the x-y plane, and as shown in FIG. 12,forms a predetermined angle γ with respect to the x-y plane. The rangeof the angle γ is determined by the relationship between the back cover6, which will be later described.

The top plate 36 is a slashed-part in FIG. 10. As shown in FIGS. 10 to12, the top plate 36 is a member integrally connected to the lower endof the joint member 35 b, and is a plate-type member almost inrectangular. In the top plate 36, radiation holes varying in shape areformed, and each of those radiation holes dissipates heat from thechassis 2.

In FIGS. 10 to 12, the upper surface of the plate 311 b is formedsubstantially flat. The rib 37 b is a member to hook a hook 713 (seeFIG. 20). In this embodiment, as an exemplary specific structure, therib 37 b is so formed, on the upper surface of the plate 311 b, as toextend along the x-axis direction and protrude to the y-axis direction.

Described next is a manner of attaching the bracket 3 b to the chassis 2with reference to FIG. 3. Into three through holes 321 b to 341 b, asingle screw is each inserted. Those screws inserted thereinto are eachfixed to the screw hole formed respectively in the bracket fixing parts23 b to 25 b. Here, when the bracket 3 b is fixed to the chassis 2, theback planes of the chassis fixing member 32 b to 34 b each abut to thebracket fixing parts 23 b to 25 b. Further, the back planes of thechassis fixing members 32 b to 34 b, as already described, form theplane flat to the x-y plane. Therefore, the bracket 3 b is securely andfirmly fixed to the chassis 2.

This is the end of the description about the bracket 3 b. Here, thebracket 3 a is substantially symmetric in shape to the bracket 3 b, andthus is neither shown nor described in detail. Here, in descriptionbelow, as for the bracket 3 a, any constituent similar in structure tothe bracket 3 b is provided with the same reference numeral. Note that,the alphabetic letter “b” found at the right end of each referencenumeral is replaced by “a”. For example, the rib formed on the bracket 3a will be a rib 3 a. The bracket 3 a is, similar to the bracket 3 b,attached to the back of the corner located at the upper right of thechassis 2.

FIG. 13 is a front view of the bracket 3 c. To make clear the relationwith FIG. 1, shown in FIG. 13 is only the bracket 3 c viewed from thedirection of the arrow B of FIG. 1. FIG. 14 is a top view of the bracket3 c, and the bracket 3 c is viewed from the direction of an arrow K ofFIG. 13. FIG. 15 is a side view of the bracket 3 c, and the bracket 3 cis viewed from the direction of an arrow L of FIG. 13. For convenienceof description below, FIGS. 13 to 15 all show an x-axis, y-axis, andz-axis being orthogonal to one another. Here, the y-axis is an axisparallel to the vertical direction. The z-x plane is a plane parallel tothe horizontal plane. Described below is about the bracket 3 c withreference to FIGS. 13 to 15.

In FIGS. 13 to 15, the bracket 3 c is injection molded and made ofinsulation. The bracket 3 c includes, generally, a frame 31 c, chassisfixing members 32 c to 33 c, a joint member 34 c, a top plate 35 c, anda cabinet fixing member 36 c. The frame 31 c is a part indicated bydots. The frame 31 c is a plate-type member almost in rectangular, andas shown in FIG. 13, the side planes thereof are indicated parallel tothe y-z plane, and the center axis thereof is indicated parallel to they-axis.

The chassis fixing members 32 c and 33 c are members used to fix thebracket 3 c to the back of the chassis 2 at the lower left. Describedbelow is an exemplary specific structure of the chassis fixing members32 c and 33 c. The chassis fixing member 32 c is in the shape of tongue,and protrudes from one end of the frame 31 c (which is upper end in FIG.13) to be parallel to the x-y plane. Formed in the chassis fixing member32 c is a through hole 321 c, a center axis of which is parallel to thez-axis (see FIG. 14). The chassis fixing member 33 c is also in theshape of tongue, and protrudes from the other end of the frame 31 c(which is lower end in FIG. 13) to be parallel to the x-y plane. Formedin the chassis fixing member 33 c is a through hole 331 c, a center axisof which is parallel to the z-axis (see FIG. 13). Here, all undersidesof the chassis fixing members 32 c and 33 c are included in the same x-yplane so that the bracket 3 c is fixable to the chassis in a firm manner(see FIG. 15).

The joint members 34 c are back-slashed parts. The joint members 34 care members to integrally couple the frame 31 c and the top plate 35 c.In this embodiment, the joint members 34 c are rod-like membersprotruding in the z direction from one end of the chassis fixing members32 c and 33 c, respectively, and from a part of the frame 31 c.

The top plate 35 c is a part covered by slashes. In this embodiment, thetop plate 35 c is a plate-type member integrally connected to the upperends of the joint members 34 c. In the top plate 35 c, several radiationholes are formed, and each of those radiation holes dissipates heat fromthe chassis 2.

The cabinet fixing member 36 c is a member used to fix the cabinet 7 tothe bracket 3 c. As an exemplary specific example, the cabinet fixingmember 36 c is structured by a rod-like member protruding along the zdirection from the lower end part of the top plate 35 c. At the tip ofthe rod-like member, a screw hole 361 c is formed.

Described next is a manner of attaching the bracket 3 c to the chassis2. Note that, this manner is similar to the one applied to the bracket 3d, and thus is described without referring to any specific drawing butto FIG. 1, and FIGS. 13 to 15. Into the through holes 321 c to 331 c, asingle screw is each inserted. Those screws inserted thereinto are eachfixed to the screw hole formed respectively in the bracket fixing parts23 c to 24 c. Here, once the bracket 3 c is fixed to the chassis 2, theback planes of the chassis fixing member 32 c and 33 c abut to thebracket fixing parts 23 c and 24 c, respectively. Further, the backplanes of the chassis fixing members 32 c and 33 c form a plane flat tothe x-y plane, therefore, the bracket 3 c is securely and firmly fixedto the chassis 2. This is the end of the description about the bracket 3c. Here, the bracket 3 d is substantially symmetric in shape to thebracket 3 c, and thus is neither shown nor described in detail. Here, indescription below, as for the bracket 3 d, any constituent similar instructure to the bracket 3 c is provided with the same referencenumeral. Note that, the alphabetic letter “c” found at the right end ofeach reference numeral is replaced by “d”. For example, the top plateformed on the bracket 3 d will be a top plate 35 d. The bracket 3 d is,similar to the bracket 3 c, attached to the back side of the cornerlocated at the lower right (see FIG. 1) of the chassis 2.

FIG. 16 is a view of the chassis 2, viewed from the side, having thebrackets 3 a to 3 d attached thereto. For convenience of descriptionbelow, FIG. 16 shows an x-axis, y-axis, and z-axis being orthogonal toone another. Here, the y-axis is an axis parallel to the verticaldirection. The z-x plane is a plane parallel to the horizontal plane.Here, to the chassis 2, presumably, the PDP 1 and the circuit board 9are attached. In FIG. 16, once the brackets 3 a and 3 b are attached tothe chassis 2, plates 311 a and 311 b are positioned in a manner as tocome directly above the periphery 22. In such case, the plates 311 a and311 b each protrude, at the tip each thereof, with respect to the plane21 of the chassis 2. Also, the ribs 37 a and 37 b are positioned towardthe front on the upper end of the chassis 2 so that a linear lineparallel to the x-axis is formed. The joint members 35 a and 35 b arepositioned on the back of the chassis 2, and rearward with respect tothe periphery 22. If this is the case, as already described, thesurfaces of the joint members 35 a and 35 b are each form thepredetermined angle γ with respect to the x-y plane. Further, thesurfaces of the joint members 35 a and 35 b are so positioned as to bein the same plane.

Also in FIG. 16, once the brackets 3 c and 3 d are attached to thechassis 2, the screw holes 361 c and 361 d are each positioned so thateach center axis thereof is parallel to the y-axis, and directly belowthe chassis 2.

With reference to FIG. 17, described next is the back cover 6 of FIG. 1.FIG. 17 is a front view of the back cover 6. FIG. 17 is a view, inrelation with FIG. 1, of the back cover 6 viewed from the direction ofthe arrow B of FIG. 1. In FIG. 17, the back cover 6 is made ofinsulation, and covers the back of the chassis 2 to which the PDP 1 hasbeen attached (see FIG. 1). The back cover 6 includes, generally, aframe 61, four joint members 62 a to 62 d. and a top plate 64 whereinfour through holes 63 a to 63 d are formed. The frame 61 is a partcovered by dots in FIG. 17, and is a frame almost in rectangular. Thejoint members 62 a to 62 d are back-slashed parts. Those joint members62 a to 62 d are plate-type members almost in rectangular, and each usedto couple the outer frame 61 to the top plate 64. The joint members 62 ato 62 d are extending diagonally up. The top plate 64 is a slashed part.The top plate 64 is a plate-type member attached over an aperture formedby the joint members 62 a to 62 d. The through holes 63 a to 63 d areeach formed at appropriate positions of the top plate 64 based on wherethe second bosses 27 a to 27 d are formed.

Here, FIG. 18 is a diagram explaining a manner of attaching the backcover 6 to the chassis 2. When attaching the back cover 6, provided area pair of spacers 121 a made of insulation. In the example of FIG. 18,the spacers 121 a are both shaped like a disk, and a through hole iseach formed in the center parts thereof. One of the spacers 121 a abutsto the surface side of the top plate 64, and the other of the spacers121 a abut to the back of the top plate 64. To be more specific, the oneand the other spacers 121 a are positioned so that the through holesmade each in the spacers 121 a positionally match to the through hole 63a. With such positioning, the through holes of the pair of spacers 121 aand the through hole 63 a together form a guiding hole which guides ascrew 122 a. Into such guiding hole, the screw 122 a is first inserted,and then the screw 122 a is fixed to the screw hole of the second boss27 a. In the same manner, screws 122 b to 122 d are fixed to the secondbosses 27 b to 27 d, respectively, through the paired spacers 121 b to121 d.

Referring now to FIG. 19, described is the electrical relationshipbetween the back cover 6 and the chassis 2. FIG. 19 shows a verticalsection of the unit having the back cover 6 attached to the chassis 2.For convenience of description below, FIG. 19 shows an x-axis, y-axis,and z-axis being orthogonal to one another. Here, the y-axis is an axisparallel to the vertical direction. The z-x plane is a plane parallel tothe horizontal plane. In FIG. 19, due to limited space, the back cover 6and the chassis are not entirely shown.

In FIG. 19, between the second boss 27 a and the periphery of thethrough hole 63 a, one of the spacers 121 a lies. Therefore, theperiphery of the through hole 63 a is not directly abutting to thesecond boss 27 a. Similarly, the other of the spacers 121 a lies betweenthe head of the screw 122 a and the periphery of the through hole 63 a,and thus the periphery of the through hole 63 a is not directly abuttingto the screw 122 a. Further, the pair of the spacers 121 a are made ofinsulation, and thus no electric continuity is established between theperiphery (conductor) of the through hole 63 a and the second boss 27 a(conductor), also electric continuity is not established between thesecond boss 27 a even if the screw 122 a lies therebetween. Between theperiphery of other through holes 63 b to 63 d and the second bosses 27 bto 27 d, electric continuity is not also established, and even if thescrews 122 b to 122 d lie therebetween, electric continuity is notestablished with the second bosses 27 b to 27 d. Further, as for partsother than the above described through holes 63 a to 63 d, the backcover 6 is attached to the chassis 2 without abutting to the chassis 2.As a result, the back cover 6 is electrically insulated from the chassis2.

FIG. 19 shows a section of a joint member 62 b. The back plane of thejoint member 62 b is a part of a plane orthogonal to the x-y plane, andforms the predetermined angle γ with respect to the x-y plane. Thisangle γ is equal to an angle formed by the surfaces of the joint members35 a and 35 b (see a dotted part) and the x-y plane. When the back cover6 is attached to the chassis 2, the back plane of the joint member 62abuts to the surface of the joint member 35 a of the bracket 3 a and thesurface of the joint member 35 b of the bracket 3 b. Therefore, from thesurfaces of the joint members 35 a and 35 b, an upward force acts withrespect to the back plane of the joint member 62. That is, the brackets3 a and 3 b support the back cover 6, while determining where to attachthe back cover 6. As such, the back cover 6 is not only screwed but alsosupported by the brackets 3 a and 3 b, thereby being securelypositioned.

FIG. 19 also shows a section of the positioning unit 10, which is only apart. Once the back cover 6 is attached to the chassis 2, the lower sidepart of the outer frame 61 abuts to the conductor blocks 103 a and 103b. Therefore, electric continuity is established between the back cover6 and the base 4, which is made of conductive materials. Note that, asalready described with reference to FIGS. 8 and 9, the base 4 and thechassis 2 are insulated from each other due to the sacs 101 a and 101 b,and thus in this part as well, the back cover 6 is completely insulatedfrom the chassis 2.

Next, the cabinet 7 shown in FIG. 1 is described. In FIG. 1, to form theappearance of the display device, the cabinet 7 is attached in suchmanner as to cover the front side of the chassis 2. In this embodiment,the cabinet 7 includes a frame 71 and a filter 72. The frame 71 is madeof insulation, and shaped like a framework. To be more specific, theframe 71 is provided with a front panel 711 and four side walls 712 a to712 d. The front panel 711 is substantially a rectangular plate, and ina center part thereof, an aperture for attaching the filter 72 isformed. The side walls 712 a and 712 c are positioned so as to beopposite to each other, and each protrude from the right side and theleft side of the front panel 711 in the direction of the arrow A. Also,the side walls 712 b and 712 d are positioned so as to be opposite toeach other, and each protrude from the upper side and the lower side ofthe front panel 711 in the direction of the arrow A. Further, the upperend and the lower end of the side wall 712 a are connected to the rightend of the side walls 712 b and 712 d, respectively. Also, the upper endand the lower end of the side wall 712 c are connected to the left endsof the side walls 712 b and 712 d, respectively.

The filter 72 passes through videos displayed by the PDP 1. The filter72 is like a plate almost in rectangular, and made of transparentmaterial typified by glass. Such filter 72 is attached to the apertureformed in the front panel 711. At this time, the filter 71 is soattached as to form a plane parallel to both the plane of the filter 72and the plane of the front panel 711.

Here, FIG. 20 shows a vertical section taken along with the line C-C′shown in FIG. 1 viewed from the direction of the arrow D. In FIG. 20, ahook 713 is formed in the side wall 712 b which is connected to theupper side of the front panel 711. The hook 713 is a rib protruding,from the back of the side wall 712 b to downward, parallel to the frontpanel 711. Also, in the side wall 712 d connected to the lower side ofthe front panel 711, an enlarged view thereof is shown in a dottedcircle, two through holes 714 a and 714 b are formed. The positions ofthose through holes are related to the positions of the screw holes 361c and 361 d.

Described next is a manner of attaching the cabinet 7 by referring toFIG. 21. First, FIG. 21(a) shows a vertical section of the chassis 2 towhich the brackets 3 a to 3 d and the back cover 6 have been attached.In such state as shown in FIG. 21(a), the part of the side wall 712 b ofthe cabinet 7 is placed over the brackets 3 a and 3 b having fixed tothe chassis 2. At this time, as shown in FIG. 21(b), the hook 713 ishooked on the ribs 36 a and 36 b. In this state, the inner side of theside wall 712 d of the cabinet 7 is matched to come to the lower planeof the brackets 3 c and 3 c. At this time, the positions of the throughholes 714 a and 714 b are matched to come to the positions of the screwholes 361 c and 361 d. As shown in FIG. 21(c), screws 715 a and 715 bare first inserted into the through holes 714 a and 714 b, and thenfixed to the screw holes 361 c and 361 d. As such, the hook 713 isengaged with and stopped by the ribs 36 a and 36 b, and thus the cabinet7 is fixed by screws at the part of the side wall 712 d. In this manner,the cabinet 7 is supported by four brackets 3 a to 3 d, and also coversthe front part of the chassis 2. As a result, the cabinet 7 and the backcover 6 form an exterior unit in Claims, and house the PDP 1 and thecircuit boards 9 fixed to the chassis 2 therein.

Here, there are two points requiring attention. A first point is that,the cabinet 7 is supported only by the brackets 3 a to 3 d, and does notabut to the chassis 2. That is, the cabinet 7 is fixed to the chassis 2via the brackets 3 a to 3 d. Further, since the bracket 3 d is made ofinsulation, the cabinet 7 is fixed to the chassis 2 in such state aselectrically insulated therefrom.

A second point is that, when fixed to the chassis 2 via the brackets 3 ato 3 d, the periphery of the cabinet 7 abuts to the periphery of theback cover 6. That is, the back cover 6 and the cabinet 7 are both madeof conductive materials, and thus electrical continuity is establishedtherebetween.

As is evident from the above, the back cover 6 and the cabinet both madeof conductive materials house the PDP 1 and the circuit 92 therein insuch state as electrical continuity is established therebetween and isinsulated from the chassis 2. Therefore, the back cover 6 and thecabinet 7 show shielding effects, and thus do not leak the EMI radiatedfrom the PDP 1 and the circuit 92 to the outside.

With such display device, as described by referring to FIGS. 1 to 6, thePDP 1 and every circuit 92 are electrically insulated from the chassis 2(see FIGS. 2 and 6). As a result, the circuits 92 are shielded from thePDP 1 thanks to the chassis 2. Also, the back cover 6 and the cabinet 7house the PDP 1 and the circuits 92 therein so that shielding effectsare achieved. As such, the present display device has the double shieldstructure. With such double shield structure, the EMI radiated from thePDP and its driving circuit is prevented from leaking to the outside ofthe display device, and further, the circuits 92 are prevented fromerroneously operating due to the EMI from the PDP 1.

Also with such display device, the PDP 1 is attached to the plane 21 ofthe chassis 2 by using the adhesive sheet 8. Thereby, the PDP 1 can befixed to the chassis 2 while the chassis 2 are kept insulated from eachother.

In the chassis 2, the first boss 26 for attaching the circuit board 9,and the second boss 22 for attaching the back cover 6 are integrallyformed. Therefore, attachment of the circuit boards 9 and the back cover6 is simplified.

Here, the complete unit does not select where to be placed, receives avideo signal transmitted from the outside, reproduces a receptionsignal, and displays a video on the screen. Here, as is well known, thesensitivity at time of receiving the video signal (radio) is preferablyhigher. In the above embodiment, the base 4 made of conductive materialsis formed to be electrically insulated from the chassis 2, andelectrical continuity is established with the back cover 6. With suchstructure, the reception sensitivity for the video signal can beimproved. Here, the applicant has compared, by experiment, the receptionsensitivity of the display device described in the present embodimentwith the reception sensitivity of a display device which is not formedto be electrically insulated from the chassis 2 and electricalcontinuity is not established with the back cover 6. Based on theexperiment result, the applicant decided to make the base 4 electricallyinsulated from the chassis 2, and establish electrical continuitybetween the base 4 and the back cover 6.

The brackets 3 a to 3 d are placed each at the corner of the chassis 2,which is almost in rectangular. The back cover 6 and the cabinet 7 aresupported. With the brackets 3 a to 3 d, neither of the back cover 6 northe cabinet 7 abuts to the chassis 2. Therefore, even if the back cover6 and the cabinet 7 of the complete unit are externally provided withimpactive forces, the provided impactive forces are absorbed by any oneof the brackets 3 a to 3 d. Thus, the main components of the displaydevice such as the PDP 1 and the circuit boards 9 can be protectedtherein.

As is obvious from the above, the base 4 supports the chassis 2 havingthe PDP 1 attached thereto to make it self-standing. The back cover 6and the cabinet 7 are each attached to the brackets 3 a to 3 d.Consequently, only the back cover 6 is removed from the complete unit,and only the cabinet 7 is removed from the complete unit. Therefore, forexample, in order to clean the inside of the filter 7, there only needsto remove the cabinet 7, and in order to change the circuit board 9,there only needs to remove the back cover 6. As such, according to thepresent display device, it is easy to access inside of the back cover 6and the cabinet 7 without removing both of those.

Here, in order to achieve more satisfactory shielding effects, theperiphery of the cabinet 7 (tip parts of the side walls 712 a to 712 d)needs to abut, completely, to the periphery of the back cover 6 (outerframe 61). In the first embodiment, however, the side walls 712 a to 712d and the outer frame 61 both small in elasticity abut to one another,and thus any gap may possibly be formed between their parts whereabutting. If there is any gap therebetween, the shielding effects may beweakened. Therefore, in a second embodiment, an object is to provide adisplay device which is capable of enhancing the shielding effects.

FIG. 22 is an exploded slanted view showing the entire structure of thedisplay device according to the second embodiment of the presentinvention. The display device of FIG. 22 is different from the displaydevice of FIG. 1 in a respect that a gasket 11 is additionally provided.Also, the side walls 712 a and 712 b of the cabinet 7 are slightlydifferent in structure. These are the only differences, and thus, inFIG. 22, any constituent corresponding to that in FIGS. 1 to 18 isprovided with the same reference numeral.

The gasket 11 is a frame almost in rectangular, and made of elasticsolid having conductivity. An exemplary structure of such elastic solidhaving conductivity, as shown in FIG. 23, is the one obtained bycovering an elastic solid 111 (see a back-slashed part) typified byrubber with a cloth 112 (see a slashed part) having conductive materialsplated thereon.

FIG. 24 is a section view showing the inside of the cabinet 7. In FIG.24, due to limited space, the cabinet 7, and the like, are not entirelyshown. Also, for convenience of description below, FIG. 24 shows anx-axis, y-axis, and z-axis being orthogonal to one another. Here, they-axis is an axis parallel to the vertical direction. The z-x plane is aplane parallel to the horizontal plane. In FIG. 24, in the side walls712 b and 712 d, stoppers 716 a and 716 b are formed. The stopper 716 band 716 d are ribs protruding substantially vertical from the inside ofthe side walls 712 b and 712 d. The stoppers 716 b and 716 d are,preferably, formed from one end of the stoppers 716 b and 716 d,respectively, to the other end thereof to be parallel to the x axis.Similarly, in the side walls 712 a and 712 c, ribs similar to thestopper 716 b are formed. Next below, the ribs formed in the side walls712 a and 712 c are referred to as stoppers 716 a and 716 c. With suchstoppers 712 a to 712 d, a ring-like rib is formed, entirely, inside ofthe cabinet 7.

The gasket 11 is adhered to the inside, entirely, of the cabinet 7 sothat the side walls 712 a to 712 d abut to the stoppers 716 a to 716 d.Therefore, once the back cover 6 and the cabinet 7 are attached to thechassis 2, the side walls 712 a to 712 d touch to the outer frame 61through the gasket 11. Thus, the gasket 11 is pushed towards the backcover 6 by the cabinet 7, and further, pushed towards the cabinet 7 bythe back cover 6. As is an elastic solid, the gasket 11 closely attachedto the back cover 6 and the cabinet 7. In other words, the gasket 11,the back cover 6, and the cabinet 7 are touched to one another ratherclose. Also, as the gasket 11 is conductive, electrical continuity iswell established between the back cover 6 and the cabinet 7.

As described in the foregoing, according to the display device of thesecond embodiment, between the back cover 6 and the cabinet 7 lies anelastic body having conductivity. Therefore, the back cover 6, thecabinet 7, and the gasket 11 are completely attached to one another, andthus the shielding effects becomes =more satisfactory between the backcover 6 and the cabinet 7.

Here, in the above embodiments, the back cover 6 is described as made ofconductive materials. However, the back cover 6 may be provided withconductivity by adhering a metallic or aluminum foil to inside of theback cover 6 made of resin.

Further, the display device may be so structured as to be a wall-hungtype.

INDUSTRIAL APPLICABILITY

The present invention is applied to a display device which displaysvideos on a screen thereof, and especially, to a display device havingan external unit structured by a back cover, cabinet, and the like,which houses a PDP (Plasma Display Panel) and its driving circuittherein so that any unwanted radiation noise is prevented from leakingto the outside, for example, to a television receiver.

What is claimed is:
 1. A display device for displaying a video on a screen thereof, comprising: a plasma display panel (hereinafter, referred to as PDP(Plasma Display panel)) structuring said screen; a circuit board on which a circuit for driving said PDP is arranged; a chassis formed like a plate made of conductive materials, to one plane thereof, said PDP is attached, and on the other plane thereof, said circuit board is mounted; and an exterior unit being conductive, and housing said PDP and said circuit board having attached to said chassis, wherein said chassis shields said circuit board so as to prevent any unwanted radiation noise emitted by said PDP from looping into the circuit on the circuit board, said exterior unit prevents, with shielding effects, the unwanted radiation noise emitted by the internally-housed PDP and the circuit on the circuit board from leaking to the outside, and said chassis and said exterior unit are electrically insulated from each other.
 2. A display device for displaying a video on a screen thereof, comprising: a plasma display panel (hereinafter, referred to as PDP(Plasma Display Panel)) structuring said screen; a circuit board having a circuit for driving said PDP is arranged on a substrate; a chassis formed like a plate made of conductive materials, to one plane thereof, said PDP is attached, and on the other plane thereof, said circuit board is mounted; a cabinet being conductive, and covering a front side of said chassis; a back cover being conductive, and covering a back side of said chassis; and a bracket being insulative, and fixed to said chassis so as to support said cabinet and said back cover, wherein said cabinet and said back cover are, when covering said chassis to which said PDP and said circuit board are fixed, supported by said bracket, electrically continued, and electrically insulated from said chassis, and thereby show shielding effects, and said chassis is electrically insulated from said circuit, and thereby, shields said circuit board and prevents the unwanted radiation noise emitted by said PDP from looping into the circuit.
 3. The display device according to claim 2, further comprising an adhesive sheet being insulative, and used to attach said PDP to said chassis.
 4. The display device according to claim 2, wherein, in said chassis, a first boss is integrally formed, said substrate is insulative, and in a predetermined position of the substrate, a through hole is formed, and said circuit board is fixed to said first boss by a screw after inserted into said through hole, and thereby, the circuit arranged on said substrate and said chassis are electrically insulated from each other.
 5. The display device according to claim 2, wherein said bracket is each attached to four corners of said chassis, and said front cover and said back cover are both supported by the four brackets attached to each of said corners.
 6. The display device according to claim 2, further comprising a base being conductive, and determining a position of said screen with respect to a placement plane by having said chassis attached thereto, wherein said base is electrically insulated from said chassis, and electrical continuity is established with said back cover.
 7. The display device according to claim 2, further comprising: a top plate positioning unit having integrally attached to said chassis, and having a cylindrical hole whose center axis is parallel to a vertical direction opened from a flat lower end plane thereof; an insulation layer formed inside, entirely, and on a lower end plane of said hole; a base being conductive, and supporting said chassis so as to determine a position of said screen with respect to a placement plane thereof; and a bottom positioning unit shaped like a rod, wherein said base includes a lug in which a through hole is formed, a center axis of the through hole is parallel to the vertical direction, and an upper end plane thereof is formed flat, said bottom positioning unit is fixed to the base by going through the through hole of said base and the hole formed in the top positioning unit, and thereby, the upper end plane of said lug determines a position of the lower end plane of the top positioning unit, and said insulation layer makes said top positioning unit and said base insulated from each other.
 8. The display device according to claim 2, further comprising a spacer made of conductive materials in which a first through hole is formed, wherein in said chassis, a second boss is integrally formed, at a predetermined position of said back cover, a second through hole is formed, and a screw inserted into said first through hole and said second through hole is fixed to said second boss, and thereby, said back cover is attached to said chassis while kept electrically insulated therefrom.
 9. The display device according to claim 5, wherein, among said four, the bracket attached on said chassis abuts to the inside of said back cover, and supports the back cover.
 10. The display device according to claim 5, wherein the two brackets fixed on said chassis are each provided with a rib, and the rest are each provided with a screw hole, said cabinet is provided with a hook on the upper part thereof, and a through hole on the lower part thereof, said hook is engaged with and stopped by said ribs, and by the screw inserted into said through hole being fixed to said screw hole, thereby said cabinet is supported by said four brackets.
 11. The display device according to claim 2, wherein said cabinet and said back cover touch to each other when supported by said brackets.
 12. The display device according to claim 2, further comprising a base for making the chassis having said PDP and said circuit board attached thereto self-standing, wherein said cabinet and said back cover are each detachable to said brackets.
 13. The display device according to claim 2, further comprising an elastic solid being conductive, wherein said cabinet and said back cover sandwich said elastic solid when supported by said brackets. 